VLP Recognization Of Combining Wavelet Transform And Independent Component Analysis

Ventricular Late Potential (VLP), which is high-frequency, low-amplitude and irregular abnormal ECG signal, appears in the terminal portion of the QRS complex and extends to ST segment. Researches show that VLP is closely associated with ventricular tachycardia (VT) and the detection of VLP has important value in precaution of sudden death after acute myocardial infraction, diagnosing asphyxia of unknown reasons, and the evaluation of medical surgery care of VT. At present, the VLP is measured using the time- and frequency-domain methods. However, the accuracy of time-domain method is affected by fixation of QRS's end which is severely disturbed by noise, and as persistence of VLP is so short that the frequency-domain method's frequency resolution is not high. To improve traditional methods, the work has been completed in this paper.Firstly, fixation of R wave by means of singularity detection with wavelet transform and confirmation the period of time of analysis. The R wave is fixed by detection of the max. of wavelet transform module plot in characteristic scales. The even symmetrical Marr wavelet overcomes limitation of detecting the zeros-crossing point of the odd symmetry wavelet transform which is apt to be disturbed by noise.Secondly , period of time is analyzed by wavelet transform. We decompose original ECG signals into a series of sub-band signals ,ICA algorithm is then applied to the sub-band signals at single or different wavelet scales to get the coefficient array components of ECG. According to time-optimization (the recursion and adjustment of the demixing matrix),the VLP recognization is extracted out of ECG signal. The experiment results show the differences between VLP positive and VLP negatively, and confirm that the VLP negatively signals are less craggedness and more regular than VLP positive, moreover, irregularity appears repeatedly.